Two-component heat-conducting gel, its preparation method and application

Abstract

The application discloses a two-component heat-conducting gel and a preparation method and application thereof. The two-component heat-conducting gel comprises an A component and a B component. The A component comprises, in terms of mass fraction, 30-100 parts of vinyl silicone oil, 100-800 parts of composite heat-conducting filler, 100-800 parts of modified heat-conducting filler, 0.1-5 parts of additive, 0.05-3 parts of platinum catalyst and 0.05-3 parts of defoaming agent. The B component comprises, in terms of mass fraction, 30-100 parts of vinyl silicone oil, 3-12 parts of hydrogen-containing silicone oil, 100-800 parts of composite heat-conducting filler, 100-800 parts of modified heat-conducting filler, 0.005-1 parts of inhibitor, 0.1-5 parts of additive and 0.05-3 parts of defoaming agent. The composite heat-conducting filler is diamond coated with nano SiO2 modified by a surface coupling agent. Through the above mode, the two-component heat-conducting gel solves the interface compatibility problem by modifying the SiO2 layer on the surface of the diamond, reduces the interface thermal resistance, enhances the mechanical properties, improves the rheological properties of the heat-conducting gel by using high-orientation nanocellulose as the additive, eliminates the cracking of the heat-conducting gel caused by thermal mismatch and prolongs the service life.

Description

Technical Field

[0001] This invention relates to the field of electronic materials technology, and in particular to a two-component thermally conductive gel, its preparation method, and its application. Background Technology

[0002] With the rapid development of the electronics industry, electronic components are becoming increasingly integrated and miniaturized. Heat dissipation has become a key factor affecting the lifespan and performance stability of these components. Therefore, to improve the heat dissipation effect inside electronic devices, thermal conductive gel is used to connect the electronic components to a heat dissipation device, which then efficiently transfers heat to the external environment.

[0003] Currently, thermally conductive gel products generally suffer from low thermal conductivity and poor storage stability. This is mainly due to the significant differences in structural properties between thermally conductive fillers and polymer resins, resulting in poor affinity and interfacial compatibility, making it difficult to form a good interfacial bond.

[0004] Currently, common silicone-based thermal conductive gel products have a tensile strength of only 0.3~0.4 MPa due to the extremely flexible molecular chains of the base polymer in silicone materials and the weak entanglement between the molecular chains. Therefore, in practical applications, thermal conductive gels must have reinforcing fillers added to the base polymer, and the fillers must be fully impregnated with the base polymer through kneading and mixing to achieve the best reinforcing effect. This process is not only complex and involves high costs for raw materials and equipment, but also imposes many stringent requirements on the content, surface structure, and performance of the reinforcing agent.

[0005] Furthermore, diamond has a thermal conductivity of 2000 W / m·K and a coefficient of thermal expansion of only (0.86±0.1)×10⁻⁶. -5 / K, which also possesses high insulation properties and excellent mechanical, acoustic, optical, electrical and chemical properties, shows great application potential in the field of microelectronic thermal conductive materials.

[0006] However, diamond has a highly stable covalent cubic crystal system. This uniform and highly ordered structure gives diamond extremely high hardness and chemical stability. At room temperature, diamond is inert to chemical reagents such as acids, alkalis, and salts, resulting in poor bonding performance between resin and diamond particles.

[0007] Currently, there are two main types of methods used for modifying the surface of diamond: 1. Metallization modification of diamond surface is carried out by means of chemical plating, electroplating or magnetron sputtering. 2. First, use strong oxidants or strong reducing agents to modify the active groups on the diamond surface, and then perform chemical grafting or physical adsorption with silane coupling agents or surfactants.

[0008] However, both methods have obvious limitations: the former, due to the metal coating on the surface, limits its application in insulating products and has high equipment investment costs; the latter relies on strong oxidants or strong reducing agents. If such reagents are lacking, the coating effect will be greatly reduced due to the chemical stability of diamond. This not only imposes strict requirements on production conditions but also hinders the realization of large-scale production. Summary of the Invention

[0009] The main technical problem solved by this invention is to provide a two-component thermally conductive gel, its preparation method and application. D-III is used as a thermally conductive filler. By modifying its surface SiO2 layer with a silane coupling agent, the interfacial compatibility is improved, the mechanical properties are enhanced, and excellent insulation is maintained. At the same time, highly oriented nanocellulose is used to utilize the directional arrangement characteristics of its oriented molecular chains to achieve the purpose of regulating rheological properties, enhancing mechanical strength and alleviating thermal mismatch stress, thereby significantly improving the thermal conductivity of the thermally conductive gel.

[0010] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide a two-component thermally conductive gel, characterized in that it comprises: component A and component B. Component A, by mass parts, includes the following raw materials: Vinyl silicone oil 30-100 parts, composite thermally conductive filler 100-800 parts, modified thermally conductive filler 100-800 parts, additives 0.1-5 parts, platinum catalyst 0.05-3 parts, defoamer 0.05-3 parts; Component B, by mass parts, includes the following raw materials: Vinyl silicone oil 30-100 parts, hydrogen-containing silicone oil 3-12 parts, composite thermally conductive filler 100-800 parts, modified thermally conductive filler 100-800 parts, inhibitor 0.005-1 part, additive 0.1-5 parts, defoamer 0.05-3 parts; The composite thermally conductive filler has a core-shell structure and includes: Diamond (DI) as the core; A nano-SiO2 coating layer is deposited on the surface of diamond to form a diamond@nano-SiO2 core-shell structure D-II; The coupling agent outer layer modified on the surface of the nano-SiO2 layer constitutes the coupling agent modified diamond@nano-SiO2 composite structure D-III; By using large-sized composite thermally conductive filler D-Ⅲ and small-sized modified thermally conductive filler to increase the packing density, small particles enter the space that large particles cannot occupy and exist in the gaps between large particles, forming more effective thermal conduction channels and a denser thermal conduction network, thereby improving the thermal conductivity.

[0011] In a preferred embodiment of the present invention, the median particle size D50 of the diamond is 10~60μm, and the diamond is at least one of spherical, near-spherical or irregular shape.

[0012] In a preferred embodiment of the present invention, the thickness of the nano-SiO2 coating layer is 2~15 nm.

[0013] In a preferred embodiment of the present invention, the composite thermally conductive filler includes the following preparation steps: (1) Preparation of SiO2 sol: Dissolve the surfactant in anhydrous ethanol, stir at 20-40℃ for 10-40 min, add TEOS, slowly add 25% ammonia water dropwise while stirring continuously, and continue the reaction for 3-8 h to obtain SiO2 sol. (2) Diamond surface coating: (21) Use diamond as the core DI, immerse it in the SiO2 sol prepared in step (1), let it stand for 1~5 min, then take it out at a pulling speed of 1~10 cm / min, and then place it in an oven at 50~80℃ to dry for 2~20 min to form a coating film. Repeat the immersion and pulling operation 1~6 times. (22) After the coating is completed, the diamond is subjected to post-heat treatment: first, gradually heat up to 100℃ and hold for 20~60min, then heat up to 600~750℃ at a heating rate of 5~10℃ / min and hold for 1~2h, and finally cool down to room temperature with the furnace to obtain the core-shell structure intermediate D-II: diamond@nano SiO2. (3) Coupling agent modification: The obtained D-II product was added to the coupling agent alcohol-water solution. During stirring, glacial acetic acid was gradually added to adjust the pH to 3-4. Then, the reaction was carried out at a constant temperature of 60-85℃ for 2-4 hours. After the reaction was completed, the product was washed 3-4 times with anhydrous ethanol, vacuum filtered and dried to obtain composite thermally conductive filler D-III: coupling agent modified diamond@nano SiO2. D-III has a reinforcing effect because the polysiloxane molecules in the silicone gel can form physical adsorption or chemical bonds with the hydroxyl groups on the surface of the SiO2 coating layer, forming a three-dimensional network structure. This restricts the deformation of the polysiloxane molecular chains in the original silicone gel, thus achieving a reinforcing effect. In addition, an excessive number of hydroxyl groups on the surface of SiO2 will form a "structuring" effect with the polysiloxane molecular chains, making the thickening effect of the silicone gel material obvious. Therefore, it is necessary to modify SiO2 with a coupling agent to reduce the number of hydroxyl groups on the surface of SiO2, thereby slowing down the thickening effect of the reinforcing agent. This improves the mechanical properties of the silicone gel while enhancing the dispersibility of D-III in the gel matrix and improving storage stability. The role of D-II heat treatment: Untreated SiO2 is a loose, dry gel powder. Heat treatment is a densification process that promotes the diffusion of trapped and unreacted substances from the pores to the particle surface, and then releases them through evaporation, decomposition, and degradation mechanisms, thereby reducing the porosity of SiO2. If the heat treatment temperature is too low, the degree of densification is low and the thermal conductivity is poor. If the heat treatment temperature is too high, the hydroxyl groups on the SiO2 surface will completely condense into siloxanes, which is not conducive to improving the mechanical properties of the silica gel.

[0014] In a preferred embodiment of the present invention, the surfactant includes at least one of polyvinylpyrrolidone (PVP), hexadecyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS), and sodium dodecyl sulfate (SDS).

[0015] In a preferred embodiment of the present invention, the coupling agent includes at least one selected from silane coupling agents, titanate coupling agents, and aluminate coupling agents; wherein, The silane coupling agent is at least one of γ-aminopropyltriethoxysilane KH550, γ-(2,3-epoxypropoxy)propyltrimethoxysilane KH560, γ-methacryloyloxypropyltrimethoxysilane KH570, and N-β-aminoethyl-γ-aminopropyltrimethoxysilane KH792. The titanate coupling agent is at least one of isopropyl triisostearate titanate GR-300, isopropyl dioleoyloxy (dioctyl pyrophosphate oxy) titanate GR-102, isopropyl trioleoyloxy titanate GR-105, and isopropyloxy tris (dioctyl pyrophosphate oxy) titanate GR-201. The aluminate coupling agent is at least one of distearyloxyisopropoxyaluminate SG-Al821 and isopropoxybis(methacryloyloxyethyl)aluminum phosphate DL-411.

[0016] In a preferred embodiment of the present invention, the vinyl silicone oil includes at least one of branched vinyl silicone oil or terminal vinyl silicone oil, and the viscosity of the vinyl silicone oil is 200~5000 mm. 2 / s, the vinyl content in the vinyl silicone oil is 0.2~5 mol%, of which: The structural formula of the branched vinyl silicone oil is: The structural formula of the end-vinyl silicone oil is: ; Where n and m are integers from 10 to 50.

[0017] In a preferred embodiment of the present invention, the hydrogen-containing silicone oil includes at least one of terminal hydrogen-containing silicone oil or branched hydrogen-containing silicone oil, and the viscosity of the hydrogen-containing silicone oil is 100~500 mm. 2 / s, the active hydrogen content in the hydrogen-containing silicone oil is 0.1~2 mol%, of which: The structural formula of the hydrogen-containing silicone oil is: ; The branched hydrogen-containing silicone oil is either branched hydrogen-containing silicone oil type one or branched hydrogen-containing silicone oil type two. The structural formula of the branched hydrogen-containing silicone oil is: , The structural formula of the branched hydrogen-containing silicone oil II is: ; Where n and m are integers from 10 to 50.

[0018] In a preferred embodiment of the present invention, the modified thermally conductive filler includes at least one of Al2O3, AlN, BN, SiC, MgO, and ZnO modified with a silane coupling agent, and the median particle size D50 of the modified thermally conductive filler is 0.3~5μm, and it is at least one of spherical, plate-like, near-spherical, or irregular shapes.

[0019] In a preferred embodiment of the present invention, the inhibitor includes any one of acetylenol, methylacetylenol, maleate, and dihexyl maleate. The platinum catalyst includes any one of Karstedt catalyst, Speier catalyst, Ashby catalyst, and Lamoreaux catalyst, and the Pt content in the platinum catalyst is 1000~8000 ppm; The defoamer is at least one of silicone-based defoamer and polyether-modified silicone-based defoamer; The additive is highly oriented nanocellulose and its derivatives, including at least one of highly oriented nanocellulose, highly oriented carboxylated modified nanocellulose, and highly oriented silanized modified nanocellulose, with a fiber diameter of 4~80nm and a fiber length of 1~30μm.

[0020] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is: to provide a method for preparing a two-component thermally conductive gel, comprising the following steps: Preparation of S1 and A components: S11, Premixing stage: Add 30~100 parts of vinyl silicone oil and 0.05~3 parts of platinum catalyst to a kneader and premix under normal pressure for 0.3~0.6 h; S12. Filler mixing stage: Heat to 60~70℃, slowly add 100~800 parts of composite thermally conductive filler, 100~800 parts of modified thermally conductive filler, and 0.1~5 parts of additives, and mix for 1~4 hours. S13. Post-processing stage: Stop heating and wait for the temperature to drop below 50℃. Add 0.05~3 parts of defoamer and continue mixing for 25~40 min. Cool to room temperature and then discharge. Preparation of components S2 and B: S21, Premixing stage: Add 30-100 parts of vinyl silicone oil to the kneader; S22. Filler mixing stage: Heat to 60~70℃, slowly add 100~800 parts of composite thermally conductive filler, 100~800 parts of modified thermally conductive filler, and 0.1~5 parts of additives, and mix for 1~4 hours; S23. Post-processing stage: Stop heating and wait for the temperature to drop below 50℃. Add 3-12 parts of hydrogen-containing silicone oil, 0.005-1 part of inhibitor, and 0.05-3 parts of defoamer. Continue mixing for 25-40 minutes, then discharge and package. S3. Molding of two-component thermally conductive gel: Mix components A and B at a mass ratio of 1:1 until homogeneous, degas under vacuum, inject into a mold and cure at room temperature for 15-24 hours to obtain a two-component thermally conductive gel.

[0021] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide an application of a two-component thermally conductive gel in the thermal management of electronic components and electronic devices.

[0022] The beneficial effects of this invention are: Using D-Ⅲ can provide both thermally conductive filler with good compatibility with the silicone gel interface and a reinforcing effect, thereby improving the mechanical properties of the silicone gel and exhibiting excellent electrical insulation properties. Using highly oriented nanocellulose and its derivatives as additives can improve the rheological properties of the two-component thermally conductive gel. Due to its high orientation, it can further improve the mechanical properties of the thermally conductive gel. At the same time, it can effectively reduce the thermal mismatch problem between the silicone gel and the thermally conductive filler, eliminate the cracking of the thermally conductive gel caused by thermal mismatch, and improve its service life. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic diagram of a preferred embodiment of the composite thermally conductive filler D-III of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0026] Unless otherwise specified, all reagents or instruments used in this invention are commercially available products.

[0027] The following is a description of some of the raw materials used in this invention: Vinyl-terminated silicone oil: viscosity 1000 mm 2 / s, with a vinyl content of 0.33mol%.

[0028] Branched vinyl silicone oil: viscosity 240 mm 2 / s, vinyl content is 1mol%.

[0029] Branched hydrogen-containing silicone oil 1: viscosity 100 mm 2 / s, with an active hydrogen content of 0.36mol.

[0030] Highly oriented nanocellulose: fiber diameter is 8nm and fiber length is 2μm.

[0031] Karstedt catalyst: Pt content is 5000 ppm.

[0032] Modified Al2O3: Median particle size D50 is 3 μm.

[0033] A method for preparing composite thermally conductive filler D-III includes the following steps: (1) Preparation of SiO2 sol: Weigh 0.1g of polyvinylpyrrolidone (PVP) and add it to a flask containing 50g of anhydrous ethanol. Stir and dissolve the PVP in a 30°C water bath for 15 minutes. After the PVP is completely dissolved, add 5mL of TEOS and then slowly add 25% ammonia water dropwise while stirring continuously. Continue the reaction for 5 hours to obtain SiO2 sol.

[0034] (2) Diamond surface coating: (21) Weigh 2g of diamond with a median particle size D50 of 50μm as the core DI, immerse it in the SiO2 sol obtained in step (1), let it stand for 1min, then pull it out of the SiO2 sol at a pulling speed of 1cm / min, and then place it in an oven at 80℃ to dry for 5min to form a coating film. Repeat the immersion and pulling coating operation twice. The coating layer thickness is 2~15nm. The coating layer thickness is controlled by the number of times it is immersed and pulled in SiO2 sol. The more times it is immersed, the thicker the coating layer is. (22) After the coating is completed, the diamond is subjected to post-heat treatment: first, the temperature is gradually increased to 100℃ and held for 30 min, then the temperature is increased to 680℃ at a heating rate of 5℃ / min and held for 1 h, and finally cooled to room temperature with the furnace to obtain the core-shell structure intermediate D-II: diamond@nano SiO2.

[0035] (3) Coupling agent modification: The obtained D-II product was added to an aqueous solution of KH570 coupling agent and stirred. During stirring, glacial acetic acid was gradually added dropwise to adjust the pH to 3.5, and then the reaction was carried out at 74°C for 4 hours. After the reaction, the sample was washed three times with anhydrous ethanol, vacuum filtered and dried to obtain composite thermally conductive filler D-III: coupling agent modified diamond@nano SiO2, such as... Figure 1 As shown; The KH570 alcohol-water solution is a mixture of KH570, anhydrous ethanol, and deionized water in a mass ratio of 10:80:20.

[0036] Example 1 This embodiment prepares a two-component thermally conductive gel. The specific preparation steps are as follows: Preparation of S1 and A components: S11, Premixing: Add 53 parts of vinyl-terminated silicone oil and 0.3 parts of Karstedt catalyst to a KL-2HV type kneader and premix under normal pressure for 0.5 h; S12. Filler mixing: Heat to 60~70℃, slowly add 180 parts of composite thermally conductive filler D-III, 120 parts of modified Al2O3, and 0.5 parts of highly oriented nanocellulose, and mix for 4 hours. S13. Post-processing: Stop heating and wait for the temperature to drop below 50℃. Add 0.1 parts of defoamer, continue mixing for 30 minutes, and discharge the material after cooling to room temperature.

[0037] Preparation of components S2 and B: S21. Premixing: Add 47 parts of vinyl-terminated silicone oil to a KL-2HV type kneader; S22. Filler mixing: Heat to 60~70℃, slowly add 180 parts of composite thermally conductive filler D-III, 120 parts of modified Al2O3, and 0.5 parts of highly oriented nanocellulose, and mix for 4 hours. S23. Post-processing: Stop heating and wait for the temperature to drop below 50℃. Add 6 parts of branched hydrogen-containing silicone oil, 0.05 parts of inhibitor, and 0.1 parts of defoamer. Continue mixing for 30 minutes, then discharge and package.

[0038] S3. Molding of two-component thermally conductive gel: Components A and B were mixed evenly at a mass ratio of 1:1, and after vacuum degassing, the mixture was injected into a mold and cured at room temperature for 18 hours to obtain a two-component thermally conductive gel.

[0039] Example 2 This embodiment prepares a two-component thermally conductive gel. The specific preparation steps are as follows: This embodiment refers to the preparation method of Example 1, except that the mass parts of composite thermally conductive filler D-III and modified Al2O3 are different. In this embodiment, both component A and component B use 100 parts of composite thermally conductive filler D-III and 200 parts of modified Al2O3.

[0040] Example 3 This embodiment prepares a two-component thermally conductive gel. The specific preparation steps are as follows: This embodiment refers to the preparation method of Example 1, except that the mass parts of composite thermally conductive filler D-III and modified Al2O3 are different. In this embodiment, both component A and component B use 200 parts of composite thermally conductive filler D-III and 100 parts of modified Al2O3.

[0041] Example 4 This embodiment prepares a two-component thermally conductive gel. The specific preparation steps are as follows: This embodiment refers to the preparation method of Example 1, except that the mass parts of composite thermally conductive filler D-III and modified Al2O3 are different. In this embodiment, both component A and component B use 360 ​​parts of composite thermally conductive filler D-III and 270 parts of modified Al2O3.

[0042] Example 5 This embodiment prepares a two-component thermally conductive gel. The specific preparation steps are as follows: This embodiment refers to the preparation method of Example 1, except that the composition and mass fraction of the vinyl silicone oil are different. In this embodiment, component A is a mixture of 40 parts of terminal vinyl silicone oil and 13 parts of branched vinyl silicone oil, and component B is a mixture of 36 parts of terminal vinyl silicone oil and 11 parts of branched vinyl silicone oil.

[0043] Comparative Example 1 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that the mass fraction of the composite thermally conductive filler D-III is different. In this example, both component A and component B use 300 parts of composite thermally conductive filler D-III, and no modified Al2O3 is added, that is, the modified Al2O3 is 0 parts.

[0044] Comparative Example 2 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that neither component A nor component B contains composite thermally conductive filler D-III, that is, the composite thermally conductive filler D-III is 0 parts, and the mass parts of modified Al2O3 are different. In this example, both component A and component B use 300 parts of modified Al2O3.

[0045] Comparative Example 3 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that an equal amount of unmodified diamond with a D50 of 50 μm is used to replace the composite thermally conductive filler D-III in Example 1. At the same time, 2 parts of fumed SiO2 are added to both component A and component B as a reinforcing agent.

[0046] Comparative Example 4 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that an equal amount of composite thermally conductive filler D-III in Example 1 is used instead of composite thermally conductive filler that has not been heat-treated at 680°C.

[0047] Comparative Example 5 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that an equal amount of composite thermally conductive filler D-III, but after 8 repeated impregnation and lifting coating treatment, is used to replace the composite thermally conductive filler D-III in Example 1.

[0048] Comparative Example 6 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that neither component A nor component B contains highly oriented nanocellulose.

[0049] Comparative Example 7 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that an equal amount of ordinary carbon nanofibers (CNF) is used to replace the highly oriented nanocellulose in Example 1.

[0050] Comparative Example 8 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that the mass fraction of highly oriented nanocellulose is different. In this example, both component A and component B use 0.05 parts of highly oriented nanocellulose.

[0051] Comparative Example 9 This comparative example prepares a two-component thermally conductive gel. The preparation method is the same as in Example 1, except that the mass fraction of highly oriented nanocellulose is different. In this example, both component A and component B use 6 parts of highly oriented nanocellulose.

[0052] Test case This experimental example demonstrates the performance testing of the prepared two-component thermally conductive gel, specifically as follows: 1. Thermal conductivity test: According to the ASTM D5470 test standard, the thermal conductivity tester purchased from Xiangtan Xiangyi was used. Three samples were tested in each group and the average value was taken. The unit is W / m·K.

[0053] 2. Tensile strength test: According to the GB / T 528-2009 test standard, the test was conducted using the Xin Sansi CMT8502 microcomputer-controlled electronic universal testing machine. Three samples were tested in each group, and the average value was taken. The unit is MPa.

[0054] 3. Volume resistivity test: The volume resistivity was tested using a ZST-121 volume resistivity meter according to ASTM D257 standard. Three samples were tested in each group, and the average value was taken. The unit is ×10⁻⁶. 13 Ω·cm. The critical volume resistivity for electrical insulation is 1.0 × 10⁻⁶. 9 Ω·cm.

[0055] 4. Dielectric constant test: The test shall be conducted in accordance with ASTM D150 using a WY2858-2 dielectric constant tester. Three samples shall be tested in each group and the average value shall be taken. The test frequency shall be 1MHz and the unit shall be kV / mm.

[0056] 5. Heat resistance aging test: Use Jinghong DHG-9423A forced-air drying oven to conduct an aging test at 150℃ / 1000h. After aging, take out the sample and observe whether it cracks.

[0057] Table 1

[0058] As can be seen from the performance comparison analysis of each embodiment and comparative example in Table 1: 1. The necessity of filler-matrix interfacial compatibility and surface modification: Because of the poor interfacial compatibility between the filler and the matrix, and the tendency of the filler to agglomerate and disperse unevenly, voids are formed at the interface, which increases the interfacial thermal resistance. Therefore, it is necessary to perform surface modification treatment on the filler to improve its dispersibility and interfacial bonding strength.

[0059] 2. Optimization of the compounding of D-Ⅲ with modified Al2O3: Examples 1-3 mainly explore the effect of the ratio of composite thermally conductive filler D-Ⅲ to modified Al2O3: When the two are mixed in an appropriate ratio, the synergistic packing of large and small particles can increase the packing density, which is beneficial for heat conduction. If too much D-Ⅲ is used, it will increase the gap between particles, reduce the effective heat conduction channels, increase the interfacial thermal resistance, and affect the heat conduction effect. If too much modified Al2O3 is used, the excess modified Al2O3 will coat around D-Ⅲ. Since its thermal conductivity is much lower than that of D-Ⅲ, it will hinder heat conduction and ultimately lead to a decrease in the thermal conductivity of the thermally conductive gel. 3. The effect of D-Ⅲ filler content: Example 4: Appropriately increasing the filling amount of D-Ⅲ can increase the contact points between the fillers, making the heat conduction network denser and improving the heat conduction performance. 4. The function of low-viscosity branched vinyl silicone oil: Example 5: Adding a small amount of low-viscosity branched vinyl silicone oil can increase the crosslinking density of silicone gel, thereby improving its mechanical properties.

[0060] The comparative examples illustrate the negative impact of different conditions on performance: 5. Disadvantages of a single packing system: Comparative examples 1 and 2 show that: When D-Ⅲ is used alone, the bulk density is low and the gaps between the filler particles are large, resulting in poor thermal conductivity. In addition, when modified Al2O3 is used alone, the tensile strength is poor because the molecular chains of the silica gel-based polymer are very flexible and the intermolecular chain entanglement is weak. 6. Interface issues in unmodified diamond: Comparative Example 3: When using unmodified diamond and reinforcing agent, the poor interfacial compatibility between diamond and silicone gel leads to high interfacial thermal resistance and poor thermal conductivity. 7. Defects of D-Ⅲ without heat treatment: Comparative Example 4: When using D-Ⅲ without heat treatment at 680℃, the SiO2 structure on the diamond surface is loose and has poor density, poor thermal conductivity, and is easy to fall off from the diamond surface during the kneading process, thus affecting the interfacial compatibility between diamond and silica gel.

[0061] 8. The effect of excessively thick SiO2 coating: Comparative Example 5: Excessive dipping and pulling cycles resulted in an excessively thick SiO2 coating, which hindered heat conduction and consequently affected thermal conductivity. The role of highly oriented nanocellulose: Comparative Example 6: Without the addition of highly oriented nanocellulose, the tensile strength is slightly lower, and after a heat aging test at 150℃ / 1000h, the thermally conductive gel will crack and powder. Comparative Example 7: Adding ordinary nanocellulose had no effect on improving tensile strength due to its poor molecular chain orientation; the thermally conductive gel with added ordinary nanocellulose cracked after a heat aging test at 150℃ / 1000h. In highly oriented nanocellulose, the oriented molecular chains are aligned along the stretching direction, forming a tighter inter-chain interaction, thereby improving the tensile strength of the thermally conductive gel and enhancing its heat aging resistance. Comparative Examples 8-9: Adding too little or too much highly oriented nanocellulose could not effectively improve tensile strength, and the thermally conductive gel also had poor heat aging resistance.

[0062] In summary, using the D-Ⅲ of this invention as a thermally conductive filler can significantly improve the interfacial compatibility between the thermally conductive filler and the silica gel, resulting in a thermal conductivity of over 20 W / m·K. Meanwhile, thanks to the good reinforcing effect of D-Ⅲ, the tensile strength can reach more than 2.5MPa, and the electrical insulation performance is also excellent; In addition, the addition of highly oriented nanocellulose and its derivatives aligns the molecular chains along the stress direction, forming a physical cross-linking network, which further enhances the tensile strength, thereby achieving the purpose of regulating rheological properties and enhancing mechanical strength. At the same time, the flexible molecular chains buffer the difference in thermal expansion, inhibit interfacial cracking, and improve the heat aging resistance of the thermally conductive gel.

[0063] The beneficial effects of the two-component thermally conductive gel of the present invention, its preparation method, and its application are as follows: Using D-Ⅲ as a thermally conductive filler can reduce the polarity difference between the thermally conductive gel and the thermally conductive filler diamond, improve interfacial compatibility, reduce interfacial thermal resistance, and utilize the reinforcing effect of the coupling agent on the diamond surface to modify the nano-silica, thereby improving the mechanical properties of the silica gel and giving the thermally conductive gel excellent electrical insulation properties. In addition, the use of highly oriented nanocellulose and its derivatives as additives improves the rheological properties of the two-component thermally conductive gel. Due to its high orientation, it can further improve the mechanical properties of the thermally conductive gel. At the same time, it can effectively reduce the thermal mismatch problem between the silicone gel and the thermally conductive filler, eliminate the cracking of the thermally conductive gel caused by thermal mismatch, and improve its service life.

[0064] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A two-component thermally conductive gel, characterized in that, include: Component A and Component B, Component A is defined as parts by mass. Including the following raw materials: Vinyl silicone oil 30-100 parts, composite thermally conductive filler 100-800 parts, modified thermally conductive filler 100-800 parts, additives 0.1-5 parts, platinum catalyst 0.05-3 parts, defoamer 0.05-3 parts; Component B, by mass parts, includes the following raw materials: Vinyl silicone oil 30-100 parts, hydrogen-containing silicone oil 3-12 parts, composite thermally conductive filler 100-800 parts, modified thermally conductive filler 100-800 parts, inhibitor 0.005-1 part, additive 0.1-5 parts, defoamer 0.05-3 parts; The composite thermally conductive filler has a core-shell structure and includes: Diamond (DI) as the core; A nano-SiO2 coating layer is deposited on the surface of diamond to form a diamond@nano-SiO2 core-shell structure D-II; The coupling agent outer layer modified on the surface of the nano-SiO2 layer constitutes the coupling agent modified diamond@nano-SiO2 composite structure D-III; The preparation steps of the composite thermally conductive filler are as follows: (1) Preparation of SiO2 sol: Dissolve the surfactant in anhydrous ethanol, stir at 20-40℃ for 10-40 min, add TEOS, slowly add 25% ammonia water dropwise while stirring continuously, and continue the reaction for 3-8 h to obtain SiO2 sol. (2) Diamond surface coating: (21) Use diamond as the core DI, immerse it in the SiO2 sol prepared in step (1), let it stand for 1~5 min, then take it out at a pulling speed of 1~10 cm / min, and then place it in an oven at 50~80℃ to dry for 2~20 min to form a coating film. Repeat the immersion and pulling operation 1~6 times. (22) After the coating is completed, the diamond is subjected to post-heat treatment: first, gradually heat up to 100℃ and hold for 20~60min, then heat up to 600~750℃ at a heating rate of 5~10℃ / min and hold for 1~2h, and finally cool down to room temperature with the furnace to obtain the core-shell structure intermediate D-II: diamond@nano SiO2. (3) Coupling agent modification: The D-II product obtained in step (22) was added to the coupling agent alcohol aqueous solution. During the stirring process, glacial acetic acid was gradually added to adjust the pH to 3-4. Then, the reaction was carried out at a constant temperature of 60-85℃ for 2-4 hours. After the reaction was completed, the product was washed 3-4 times with anhydrous ethanol, vacuum filtered and dried to obtain composite thermally conductive filler D-III: coupling agent modified diamond@nano SiO2. The modified thermally conductive filler includes at least one of Al2O3, AlN, BN, SiC, MgO, and ZnO modified with silane coupling agent. The median particle size D50 of the modified thermally conductive filler is 0.3~5μm, and it is at least one of spherical, plate-like, near-spherical, or irregular shapes. The additive is highly oriented nanocellulose.

2. The two-component thermally conductive gel according to claim 1, characterized in that, The median grain size D50 of the diamond is 10~60μm, and the diamond is at least one of spherical, near-spherical or irregular shape.

3. The two-component thermally conductive gel according to claim 1, characterized in that, The thickness of the nano-SiO2 coating layer is 2~15 nm.

4. The two-component thermally conductive gel according to claim 1, characterized in that, The surfactant includes at least one of PVP, CTAB, SDBS, and SDS.

5. The two-component thermally conductive gel according to claim 1, characterized in that, The coupling agent includes at least one selected from silane coupling agents, titanate coupling agents, and aluminate coupling agents; wherein... The silane coupling agent is at least one of KH550, KH560, KH570, and KH792; The titanate coupling agent is at least one of GR-300, GR-102, GR-105, and GR-201; The aluminate coupling agent is at least one of SG-Al821 and DL-411.

6. The two-component thermally conductive gel according to claim 1, characterized in that, The vinyl silicone oil includes at least one of branched vinyl silicone oil or terminal vinyl silicone oil, and the viscosity of the vinyl silicone oil is 200~5000 mm. 2 / s, the vinyl content in the vinyl silicone oil is 0.2~5 mol%, of which: The structural formula of the branched vinyl silicone oil is: The structural formula of the end-vinyl silicone oil is: ; Where n and m are integers from 10 to 50.

7. The two-component thermally conductive gel according to claim 1, characterized in that, The hydrogen-containing silicone oil includes at least one of terminal hydrogen-containing silicone oil or branched hydrogen-containing silicone oil, and the viscosity of the hydrogen-containing silicone oil is 100~500 mm. 2 / s, the active hydrogen content in the hydrogen-containing silicone oil is 0.1~2 mol%, of which: The structural formula of the hydrogen-containing silicone oil is: ; The branched hydrogen-containing silicone oil is either branched hydrogen-containing silicone oil type one or branched hydrogen-containing silicone oil type two. The structural formula of the branched hydrogen-containing silicone oil is: , The structural formula of the branched hydrogen-containing silicone oil II is: ; Where n and m are integers from 10 to 50.

8. The two-component thermally conductive gel according to claim 1, characterized in that, The inhibitors include any one of acetylenol, methylacetylenol, maleate, and dihexyl maleate. The platinum catalyst includes any one of Karstedt catalyst, Speier catalyst, Ashby catalyst, and Lamoreaux catalyst, and the Pt content in the platinum catalyst is 1000~8000 ppm; The defoamer is at least one of silicone-based defoamer and polyether-modified silicone-based defoamer; The highly oriented nanocellulose has a fiber diameter of 4~80nm and a fiber length of 1~30μm.

9. A method for preparing a two-component thermally conductive gel as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Preparation of S1 and A components: S11, Premixing stage: Add 30~100 parts of vinyl silicone oil and 0.05~3 parts of platinum catalyst to a kneader and premix under normal pressure for 0.3~0.6 h; S12. Filler mixing stage: Heat to 60~70℃, slowly add 100~800 parts of composite thermally conductive filler, 100~800 parts of modified thermally conductive filler, and 0.1~5 parts of additives, and mix for 1~4 hours. S13. Post-processing stage: Stop heating and wait for the temperature to drop below 50℃. Add 0.05~3 parts of defoamer and continue mixing for 25~40 min. Cool to room temperature and then discharge. Preparation of components S2 and B: S21, Premixing stage: Add 30-100 parts of vinyl silicone oil to the kneader; S22. Filler mixing stage: Heat to 60~70℃, slowly add 100~800 parts of composite thermally conductive filler, 100~800 parts of modified thermally conductive filler, and 0.1~5 parts of additives, and mix for 1~4 hours; S23. Post-processing stage: Stop heating and wait for the temperature to drop below 50℃. Add 3-12 parts of hydrogen-containing silicone oil, 0.005-1 part of inhibitor, and 0.05-3 parts of defoamer. Continue mixing for 25-40 minutes, then discharge and package. S3. Molding of two-component thermally conductive gel: Mix components A and B at a mass ratio of 1:1 until homogeneous, degas under vacuum, inject into a mold and cure at room temperature for 15-24 hours to obtain a two-component thermally conductive gel.

10. The application of a two-component thermally conductive gel as described in any one of claims 1 to 8 in the thermal management of electronic components and electronic devices.

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